This invention relates to multilayer or laminated buss bars which include incorporated capacitors or condensers. More particularly, this invention relates to an improved high capacitance laminated buss bar with incorporated capacitors wherein the buss bar has superior temperature and frequency properties and is inexpensive to manufacture as compared to buss bars of the prior art.
With the trend towards large scale piling of integrated circuits in addition to the high density packaging of electronic parts on circuit boards, the power supply buss bars and signal supply buss bars are required to have low inductance and low characteristic impedance and high distributive capacitance in order to avoid the undesirable effects of high frequency noise.
Laminated buss bars in which conductor layers are interleaved and spaced with an insulating film of relatively high dielectric constant are known for use as power supply and signal supply components, these components commonly being referred to as multilayer or laminated buss bars. However, the dielectric materials normally used as the interleaved insulating spacer have limits as to dielectric constant and or distributed capacitance. The use of materials of very high dielectric constant has been proposed, but such materials have limitations, primarily as to cost.
In U.S. Pat. No. 4,266,091, all of the contents of which are incorporated herein by reference, a laminated buss bar is disclosed with incorporated capacitors which result in a significantly improved power or signal distribution system. U.S. Pat. No. 4,266,091 involves the direct incorporation in the buss bar of capacitors which preferably consist of relatively thick ceramic chips, i.e., between about 0.1 to 0.3 millimeters. These relatively thick chips must also have a high dielectric constant. While buss bars constructed in accordance with U.S. Pat. No. 4,266,091 offer significant advantages, limitations exist in that temperature characteristics and frequency characteristics can only be improved by the use of expensive chips. Thus, for reasons of economy, inexpensive chips have had to be generally employed, at a sacrifice of properties such as temperature and frequency. Yet another problem of the buss bars of U.S. Pat. No. 4,266,091 is that the capacitor chips are usually fixed to the conductors by a suitable adhesive. As a result of this need for the application of adhesive, the number of process steps increases and hence the cost of manufacture increases.